This invention relates to plastic vehicle bumpers and more particularly to supports for attaching plastic bumpers to the steel struts of a motor vehicle frame.
Currently attachment of plastic bumpers to the body of a motor vehicle, such as an automobile with or without the use of shock absorbers, typically requires use of bolts for attaching the plastic bumper back face to the steel face of the strut extending from the automobile body. This has several disadvantages. First, holes are introduced in a region of high stresses resulting in unnecessary stress concentration in the plastic material. Second, slight variations on the amount of torque applied while tightening the bolt could result in excessive loads on the plastic which, in addition to giving rise to high stresses, could also introduce cracks. Third, such joints cannot be sealed properly and the resulting crevices could act as traps for solvents and other environmental agents that attack the plastic material, resulting in failure due to material degradation. Finally, the current approaches for attachment are cumbersome from the point of view of assembly, probably being based on how metal bumpers are assembled and attached to the supports.
It is an object of the present invention to provide an attachment support for attaching a plastic bumper to the metal frame of a motor vehicle, while avoiding any need for making holes in the plastic bumper.
It is a further object of the present invention to provide a sealed interface between the metal and plastic parts of a plastic bumper at the bumper support to avoid material degradation due to trapped solvents or environmental agents.